The present invention relates to metal coordination complexes having constrained geometry. The invention also relates to certain novel addition polymerization catalysts comprising such metal complexes having constrained geometry. Furthermore, the invention relates to methods for the polymerization of addition polymerizable monomers and to the resulting polymers.
Because of the unique exposure of the active metal site of the metal coordination complexes having constrained geometry, catalysts resulting therefrom have unique properties. Under certain conditions, the catalysts of the invention are capable of preparing novel olefin polymers having previously unknown properties due to their unique facile abilities to polymerize .alpha.-olefins, diolefins, hindered vinylidene aliphatic monomers, vinylidene aromatic monomers and mixtures thereof.
Numerous metal coordination complexes are known in the art including such complexes involving monocyclopentadienyl groups and substituted monocyclopentadienyl groups. The present metal coordination complexes differ from those previously known in the art due to the fact that the metal is bound to a delocalized substituted .PI.-bonded moiety in a manner so as to induce a constrained geometry about the metal. Preferably the metal is bound to a cyclopentadienyl, substituted cyclopentadienyl or similar group by both a .eta..sup.5 -bond and a bridging linkage including other ligands of the metal. The complexes also preferably include metals having useful catalytic properties.
Also previously known in the art are transition metal coordination complexes known as tucked complexes. Such complexes are described in Organometallics 6, 232-241 (1987).
In U.S. Ser. No. 8,800, filed Jan. 30, 1987 (published in equivalent form as EP 277,004) there are disclosed certain bis(cyclopentadienyl) metal compounds formed by reacting a bis(cyclopentadienyl) metal complex with salts of Bronsted acids containing a non-coordinating compatible anion. The reference discloses the fact that such complexes are usefully employed as catalysts in the polymerization of olefins. For the teachings contained therein U.S. Ser. No. 8,800 and EP 277,004 are herein incorporated in their entirety by reference thereto.
Previous attempts to prepare copolymers of vinylidene aromatic monomers and .alpha.-olefins, in particular copolymers of styrene and ethylene, have either failed to obtain substantial incorporation of the vinylidene aromatic monomer or else have achieved polymers of low molecular weight. In Polymer Bulletin, 20, 237-241 (1988) there is disclosed a random copolymer of styrene and ethylene containing 1 mole percent styrene incorporated therein. The reported polymer yield was 8.3.times.10.sup.-4 grams of polymer per micromole titanium employed.
It has now been discovered that previously known addition polymerization catalysts are incapable of high activity and polymerization of numerous monomers because they lack constrained geometry.
It would be desirable if there were provided novel complexes of groups 3 (other than scandium), 4-10 and the lanthanides having constrained geometry.
Additionally it would be desirable if there were provided novel catalysts for addition polymerizations comprising novel complexes of groups 3 (other than scandium), 4-10 and the lanthanides having constrained geometry.
Furthermore, it would desirable if there were provided a process for the preparation of polymers of addition polymerizable monomers using novel catalysts comprising complexes of groups 3 (other than scandium), 4-10 and the lanthanides having constrained geometry.
Finally , it would be desirable if there were provided novel polymers of addition polymerizable monomers that may be prepared by an addition polymerization process using catalysts comprising novel complexes of groups 3 (other than scandium), 4-10 and the lanthanides having constrained geometry.